Depyrogenation using Plasmas: A Novel Approach for Endotoxin Deactivation Using a Dielectric Barrier Discharge at Atmospheric Pressure.

Developing a low-cost depyrogenation process is vital in extending medical applicability of polymers that can be used in medicine. We present an overview of the plasma-based depyrogenation literature and address the need to develop a non-thermal plasma-based depyrogenation process for delicate materials such as chitosan. We present a low-cost plasma apparatus to treat chitosan powder in hermetically sealed bags. We decouple the experiments into two; depyrogenation experiments for dried standard endotoxin on glass slides, and chitosan modifications analysis through FTIR spectroscopy. We demonstrate depyrogenation efficacy with up to a 4-log reduction in endotoxin levels and discuss minor changes observed in plasma-treated chitosan.

PDGFB-based stem cell gene therapy increases bone strength in the mouse.

Substantial advances have been made in the past two decades in the management of osteoporosis. However, none of the current medications can eliminate the risk of fracture and rejuvenate the skeleton. To this end, we recently reported that transplantation of hematopoietic stem/progenitor cells (HSCs) or Sca1(+) cells engineered to overexpress FGF2 results in a significant increase in lamellar bone matrix formation at the endosteum; but this increase was attended by the development of secondary hyperparathyroidism and severe osteomalacia. Here we switch the therapeutic gene to PDGFB, another potent mitogen for mesenchymal stem cells (MSCs) but potentially safer than FGF2. We found that modest overexpression of PDGFB using a relatively weak phosphoglycerate kinase (PGK) promoter completely avoided osteomalacia and secondary hyperparathyroidism, and simultaneously increased trabecular bone formation and trabecular connectivity, and decreased cortical porosity. These effects led to a 45% increase in the bone strength. Transplantation of PGK-PDGFB-transduced Sca1(+) cells increased MSC proliferation, raising the possibility that PDGF-BB enhances expansion of MSC in the vicinity of the hematopoietic niche where the osteogenic milieu propels the differentiation of MSCs toward an osteogenic destination. Our therapy should have potential clinical applications for patients undergoing HSC transplantation, who are at high risk for osteoporosis and bone fractures after total body irradiation preconditioning. It could eventually have wider application once the therapy can be applied without the preconditioning.

Vertebral body fractures after transpsoas interbody fusion procedures.

BACKGROUND CONTEXT: Although the frequency of transpsoas lumbar interbody fusion procedures has increased in recent years, complication reports remain scarce in the literature. PURPOSE: To present four cases of vertebral body fracture after transpsoas interbody fusion procedures in nonosteoporotic patients without significant trauma and discuss relevant biomechanical factors. STUDY DESIGN: Case series and literature review. PATIENT SAMPLE: Patients 1 and 2 were obese men who underwent one- and two-level transpsoas interbody fusion procedures and subsequently experienced coronal plane fracture. Patients 3 and 4 were elderly women who underwent multilevel transpsoas interbody fusion procedures and experienced L5 compression fracture. RESULTS: Patients 2 and 3 were treated nonsurgically after fracture. The fractures healed uneventfully; however, Patient 3 developed a flat back syndrome. Patient 1 underwent posterior instrumented fusion and had solid bridging bone above and below the fracture. Patient 4 was treated with vertebroplasty. Factors potentially contributing to these fractures were discussed. CONCLUSIONS: Fracture can occur after transpsoas lumbar interbody fusion, even in nonosteoporotic patients. Factors, such as intraoperative end-plate breach, subsidence, compression by lateral screws, and cage rolling, could contribute to the development of fractures after transpsoas interbody fusion.